1. Field of the Invention
The present invention relates to a method for forming a resist pattern and also to a method for manufacturing a semiconductor device using the formation method. More particularly, the invention relates to a method for forming a resist pattern wherein a chemically amplifying resist is patterned accurately on an underlying film containing a basic substance and also to a method for manufacturing a semiconductor device using the formation method.
2. Background Art
FIG. 10 and FIG. 11 are, respectively, a sectional view showing a conventional method of manufacturing a semiconductor device using a chemically amplifying resist. Referring now to FIG. 10(a), a film 103 to be processed, an antireflection film 105 and a positive type of chemically amplifying resist 107 are successively formed on a semiconductor substrate 101. Next, with reference to FIG. 10(b), the semiconductor substrate 101 is irradiated with an excimer laser beam 111 via a photomask 109 of a desired pattern for exposure of the chemically amplifying resist 107 thereto. Upon the exposure, proton acid H+ is generated in the chemically amplifying resist 107 at an exposed portions 107a thereof which has been irradiated with the beam. This proton acid acts as a catalyst that causes a resist resin or the like to undergo a chemical change and convert it to a substance capable of being dissolved in a liquid developer.
Next, with reference to FIG. 10(c), the exposed, chemically amplifying resist 107 is developed to permit exposed portions 107a to be dissolved and non-exposed portions 107b to be left, thereby forming a resist pattern 107c. Referring now to FIG. 11(a), an antireflection film 105 is etched by using a mask of the resist pattern 107c to form an antireflection film pattern 105b. 
Thereafter, reference is made to FIG. 11(b) wherein the film 103 to be processed is etched by using a mask of the resist pattern 107c and the antireflection film pattern 105b, thereby obtaining a desired pattern 103a of the film to be processed. Subsequently, the resist pattern is removed, followed by a given process to complete a desired semiconductor device.
In such prior art techniques as set forth above, however, when the antireflection film as an underlying film of the chemically amplifying resist, contains a basic substance which is liable to supply an electron, the solubility of the resist in a liquid developer lowers by a so-called acid deactivation phenomenon wherein the proton acid (H+) generated in the resist undergoes a neutralization reaction with the electron supplied from the antireflection film at the interface between the resist and the antireflection film as shown in FIG. 12.
As a result, as shown in FIG. 10(c), the resist pattern 107c takes a form of a trailed skirt at the lower portion thereof. When the film to be processed is etched by using a mask of such a resist pattern, the resultant film pattern may become thicker than that of a desired size, or may take such a step-shifted shape that its shoulder portion is slanted downwards, thus presenting the problem that the control of dimensional accuracy becomes difficult. It will be noted that the above-mentioned chemically amplifying resist has been assumed to be of the positive type (wherein an exposed portion is dissolved in a liquid developer) and that with a negative type (wherein a non-exposed portion is dissolved in a liquid developer), the resist pattern becomes thinner at the lower portion thereof, with the result that a similar problem has been experienced in that the resist pattern may be liable to fall down, or the pattern of the film to be processed may become finer.
The present invention has been made in order to solve such problems as discussed above and a first object of the invention is to provide a method for forming a resist pattern which ensures the formation of an accurate resist pattern even on an underlying film containing a basic substance.
A second object of the invention is to provide a method for manufacturing a semiconductor device using the above resist pattern-forming method.
According to one aspect of the present invention, in a method for forming a resist pattern, a surface of an underlying film containing a basic substance is treated by exposure to a plasma using a carbon-containing gas. A chemically amplifying resist is formed on the surface-treated underlying film. The chemically amplifying resist is subjected to exposure and development treatments thereby patterning said chemically amplifying resist.
According to another aspect of the present invention, in a method for forming a resist pattern, a surface of an underlying film containing a basic substance is treated by exposing to an ozone gas. A chemically amplifying resist film is formed on the thus surface-treated underlying film. The chemically amplifying resist is subjected to exposure and development treatments thereby patterning said chemically amplifying resist.
According to another aspect of the present invention, in a method for forming a resist pattern, a surface of an underlying film containing a basic substance is treated by exposing to an oxygen-containing high temperature gas. A chemically amplifying resist film is formed on the thus surface-treated underlying film. The chemically amplifying resist is subjected to exposure and development treatments thereby patterning said chemically amplifying resist.
According to another aspect of the present invention, in a method for forming a resist pattern, an underlying film containing a basic substance is formed on a substance. A chemically amplifying resist film is formed on the underlying film. The chemically amplifying resist is subjected exposure and development treatments thereby patterning the chemically amplifying resist. The exposure is performed in such a state that the substrate is applied with a potential by voltage application means thereby causing the underlying film to be polarized.
Other and further objects, features and advantages of the invention will appear more fully from the following description.